We propose to continue developing and testing the non-invasive method of high-frequency (1 to 100 Hz) sinusoidal forced oscillations for quantifying impedance of the respiratory systems of normal humans and animals, of human with early small airways disease, and of animals with introgenic interventions and varied autonomic efferent activity affecting the lung. Values of resistive compliance and inertance elements of impedance estimated by this non-invasive method will be compared with values obtained by more conventional and invasive means. An electrical analogue to predict impedance of the respiratory system will be developed from measurements of pressure and flow obtained by experimentation. The validity of the model will be assessed by the capability of the analogue to explain pressure-flow relationships in varying physiological states induced by alterations in the respiratory system.